Rotor mounting means for variable tuning devices



J. H. TEAF April 17, 1945.

2 Shet-Sheet 1 Filed June 15, 1945 Gttorncg April 17, 1945. J. H. TEAF ROTOR MOUNTING MEANS FOR VARIABLE TUNING DEVICES Filed June 15 1945 2 Sheets-Sheet 2 Patented Apr. 17, 1945 RUTOR MOUNTING MEANS FOR VARIABLE TUNING DEVICES John H. Teaf, Colwick, N. J., assignor, by mesne assignments, to Condenser Development Corporation, Newark, N. J., a corporation of New Jersey Application June 15, 1943, Serial No, 490,829

12 Claims.

This invention relates to means for mounting the rotatable member of a variable tuning device such as a condenser.

The improvement to be hereinafter described is especially directed to the mounting of a rotor in a condenser which is used in connection with radio apparatus to be used on military machines such as tanks, trucks and tractors, which are subject to enormous strains and vibrations. For such use it ha been found that the ordinary means of mounting the rotor of a condenser are not satisfactory, and to meet the requirements for such strenuous service, the rotor to which this application is directed is carried by a shaft supported by annular non-separable precisiontype ball bearings; and even though this highestclass ofv bearing is utilized, additional means must be resorted to in order to get proper alignment of the bearings which carry the rotor shaft in their support members.

Designs of shaft bearing mountings in the past have depended solely upon precise machining of parts to obtain the degree of alignment necessary to provide uniformity of torque and constant stress in the frame of the condenser throughout the rotation of the shaft, such that a definite relation between capacitance and rota'tion exists at all times. Improper bearing alignment and the resulting non-uniformity in rotational torque as well as the ensuing frame stress variations cause corresponding errors in the intended graph of capacitance against rotation.

It is therefore the general object of my invention to provide means for mounting rotor shaft bearing of the type described so as to get a free constant torque and uniform rotation in the shaft, whereby the greatest efiiciency and life may be obtained from a condenser or variable tuning device employing a rotatable shaft.

It is the further object of this invention to provide a combination of design features such that adjustments of alignment of bearings is provided, thus permitting the use of parts requiring less accuracy in themselves. Further features involving ease of machining, mass production methods, low cost, will be apparent to those skilled in the art.

In order to attain this general object, I have provided a construction, to be later described in detail, which will allow at least one of the bearings to be adjusted after it has been installed in its support member on the tuning device, but, if necessary, both bearings may be similarly adjusted. This adjustment is provided by screws carried by the bearing support member in such a position as to engage the outer race of the bearing in order to secure as nearly perfect parallelism of the planes of contact of the balls of the two bearings as possible.

In adjusting the screws against the outer race, if one or more of them is turned in too far, a thrust will be set up due to the strain set up through the frame support member, and it will be noticed that the shaft torque is non-uniform. In this case the screws will need to be backed off whereby the outer race will follow within limits and in accordance with the strain in the frame support member, it being understood that the outer race has what might be termed an easily sliding fit in its support member.

In my work with this type of rotor mounting, I have found that the following possibility may exist when the adjustment, to be described later in detail, is applied only to one end, for example the rear end, of the condenser. This possibility is based on the assumption that the front end bearing is slightly out of alignment with the rear end bearing, which will produce a variable plane of rotation for the front bearing, so that when the screws at the rear or opposite end of the condenser are adjusted, another inclined plane degrees out of phase with the inclined plane at the front endmay be produced, such that they balance each other and thus eliminate the onearound torque variation that may be felt before adjustment is madt and under some circumstances this phasing action may take place.

However, I believe that the advantages of the single-end adjustment lie in these facts: First, the bearing at the front end will not be very far out of perpendicular alignment with the rearend hearing when it is remembered that the greatest care is used in the machining and assembly of the frame support members where separate support members are used. Second, any misalignment at the end of the adjustment operation will be extremely small. Third, since the adjustment is made to take care of a slight physical condition, the phasing action of the bearings is the easiest to handle and the amount of misaligmnent, which would be purposely introduced in the rear bearing to match that at the front bearing, would actually be extremely dimensionally negligible.

How the general object of the invention is at tained, will be better understood by reference to the annexed drawings, wherein:

Figure l is a part elevational and part sectional view through the frame and shaft which carries the rotor structure (the stator plates of the condenser for which the frame is especially designed are not shown since they form no part of the present invention).'

Figure 2 i a view of Figure 1,.looking from right to left.

Figure 31s a view of Figure 1, looking from left to right. 7

Figure 4 is a view on the line 4-4 of Figure 1.

Figure 5 is a View looking at the inner side of the covering plate shown on the right hand support plate of Figure 1.

Figure 6 is a view similar to the right hand bearing shown in Figure 1, but on an enlarged scale and illustrating a slight modification.

Figure 7 is part sectional and part elevational view of a modified construction, and

Figure 8 i a view similar to Figure 7 but of ceive a ball bearing 6 having an inner race I and i an outer race 8, The bearing" used in the construction described herein is of the annular, ra-

dial, non-separable, precision type of ball bearing and the frame support members I and 2 are machined so that the outer race 8 has relatively easy sliding fit thereinto, while the inner race I has a relatively tight fit on the end of the rotor shaft 9. Positioned on the outer surface of the frame of the support member I and the vbearing 6, is a cover plate Hi. This is formed or machined with two portions which are concentrically arranged with respect to the axis of theshaft 9. The outer concentric portion H actsas a stop for the outer race 8, while the inner concentric portion l2 has an outboard clearance therearound free from the adjacent inner race 1.

The rear support member 2 has mounted thereon a cup-shaped plate l3, the same being held to the support member 2 as by screws 27. The

cover plate l3 overlies a bearing 6 similar in all ferent means for holding the screws in adjusted position may be utilized, That shown in Figure 1 comprises a metallic disc l5 whichis held to the cover plate 13 as by rivets 26, three of which are shown in Figure 2. Between the disc l5 and cover plate 13 is a disc [6 of some suitable pliable material such as Bakelite, into which the screws l4 cut a thread when they are inserted.

The disc I5 has clearance holes therein through which the screws l4 may pass into engagement with the outer race 8 of the bearing.

By careful adjustment of the screws It the outer race 8 of the rear bearing may be adjusted to secure the constant torque and uniform rotation of the shaft 9. No matter how carefully the frame members are machined and assembled,

there is bound to be some displacement, even though it may be slight and with this type of bearing .1 have found that such adjustment as just described or the equivalent thereof is necessary with this type of a bearing as it differs from the ordinary cup-and-cone bearing wherein the balls may find a seat to take care of some misalignment.

If desired the inner surfaces of the support member I and 2 may be provided with dust covers I! for the bearing which may be held to the support members in any satisfactory manner as by screws, nuts and lock washers generally referred to as J8.

In the enlarged form shown in Figure 6, a modi- Y jections 20 will cause the race 8 to follow the screws 14 and thereby bring the balls onto their line contact between the two races 1 and 8;

In the form shown in Figure 7 the frame is an integral structure. The front end support mem- 1 ber'l is machined to obtain the two concentrically arranged surfaces H and 12, the same as in Figure 1. The rear bearing is overlapped by v a cover plate 21 which is fastened to the end support'member 2 by screws 22. Each screw l4, however, is held in adjusted position by a nut 23 and lock washer 24 but the functioning of the screws I4 is the same as heretofore described.

The screws M may be held in adjusted position by a non-corrosive cement such as Gyptol, in

which case the retaining disc l6 need not be used.

Another arrangement is shown in Figure 8, wherein the end support member I is machined as in Figure l and is provided with a cover plate 10 similar to that shown in Figure 1, while the rear support member 2 has a projection case 25 integral therewith for receiving the adjusted screws I 3. While the constructions shown in Figures? and 8 are more difiicult to manufacture than the form shown in Figure 1, they do illustrate how modifications of the invention may be made withoutdeparting from the spirit of the same.

What I claim is:

1. Means for mounting a shaft between two spaced support members on precision ball bearings of the so -callednon-separable radial type in order to get free constant torque and uniform rotation of the shaft; said means including a plate fastened to the outer surface of one of the support members and overlying a bearing of the type mentioned positioned ma. hole in said support member, th plate having an opening through which said shaft may project and having two portions concentrically arranged with respect to said opening and each other, said portions being formed outwardly from the face of the plate which engages said support member, the outer radial portion being in circumferential engagement with the outer race of the bearing, Whilethe inner radial portion is spaced away from the inner face, said means also including a cup-shaped cover plate fastened to the outer surface of the other of said support members and overlying a bearing of the type mentioned positioned in a hole in said member in axial alignment with the hole and bearing in the first-mentioned support member, said cup-shaped cover carrying a plurality of screw-threaded members spaced so as to engage the outer race of the associated bearing, and means for locking said screwthreaded members in adjusted position.

2. Means for mounting a shaft as set forth in claim. 1, further characterized in that the screwthreaded members are greater than two in number and arranged on the same circle around the shaft axis.

3. Means for mounting a shaft as set forth in claim 1, further characterized in that the screwthreaded members are at least three in number and arranged in equally spaced degrees on the same circle around the shaft axis.

4. Meansfor mounting a shaft as set forth in claim 1, further characterized in that the screwthreaded members are at least three in number and'arranged in equally spaced degrees on the same circle around the shaft axis, while said means for locking the screw-threaded members in place includes a disc of strong non-metallic material capable of having a good gripping thread cut therein by the screw-threaded members as they are screwed thereinto.

5. Means fOr mounting a shaft as set forth in claim 1, further characterized in that the screwthreaded members are at least three in number and arranged in qually spaced degrees on the same circle around the shaft axis, while said means for locking the screw-threaded members in place includes a disc of strong non-metallic material held to the base of the cover by an internally positioned metal disc having fastening means passing therethrough and through the non-metallic disc and the cover.

6. Means for mounting a shaft as set forth in claim 1, further characterized in that dust-protecting plates are fastened over each bearing on the interior parts of said support members.

'7. Means for mounting a shaft as set forth in claim 1, further characterized in that dust-protecting plates are fastened over each bearing on the interior parts of said support members, the dust-protecting cover at the rear bearing having resilient portions which engage the outer race of the bearing at points preferably opposite the said screw-threaded members.

8. Means for mounting a shaft between two spaced support members on precision ball bearings'of the so-called non-separable radial type in order to get free constant torque and uniform rotation of the shaft; said means including one of said support members having a hole for a bearing of the type mentioned, an annular shoulder overlapping the boundary of said hole against which the outer race of the bearing seats, and a further annular shoulder spaced inwardly from the first shoulder toward the axis of the bearing but spaced outwardly away from the inner race, a cover plate fastened to the outer surface of the other of said support members and overlying a bearing of the type mentioned positioned in a hole in said member in axial alignment with the hole and bearing in the first-mentioned support member, said cover plate carrying a plurality of screw-threaded members spaced so as to engage the outer race of the associated bearing, and means for locking said screw-threaded members in adjusted position.

9. Means for mounting in a frame having bearing support members, the shaft of a rotatable tuning member on precision ball bearings of the so-called non-separable radial type in order to get free constant torque and uniform rotation of the shaft; said means including at least one of said support members having cover means on the outer surface of one of said support members and overlying a bearing of the type mentioned positioned in a hole in said member said cover means carrying a plurality of adjustable members spaced so as to arcuately engage the outer race of the associated bearing, means for locking the said adjustable members in adjusted position and a bearing of the type mentioned carried in another support member in alignment with the firstmentioned bearing, said second-mentioned bearing, if no adjustment of this bearing is necessary, having an outwardly positioned stop surface for its outer race while the inner race has an outboard clearance therearound.

10. Means for mounting the shaft of the rotatable part of a radio tuningdevice on bearings as set forth in claim 9 further defined in that the frame and support members are all in one piece with the front bearing having its outer race in engagement with an annular surface of the frame support member while the inner race has an outboard clearance therearound and the rear bearing is as defined in claim 9.

11. Means for mounting the shaft of the rotatable part of a radio tuning device on bearings as set forth in claim 9 further defined in that the frame and support members are all in one piece with the front bearing having its outer race in engagement with an annular surface of a removable cover while the inner race is free from engagement with the cover and the rear support member has an integral projecting part over the bearing for carrying the adjustable members.

12. In a framework for carrying a radio tuning device having stationary and movable parts,

means for mounting the shaft of the movable part in portions of the framework on two bearings of the type herein described so as to get a proper phase relation between the two bearings whereby a smooth turning shaft may be obtained, said means including shoulders on the shaft near its opposite ends and against which the inner faces of the inner races of said bearings are positioned, while the outer faces of said inner races have a clearance all around, means independent of the balls for applying, axially of the shaft, oppositely acting forces, one to each face of the outer race of at least one of said bearings, one of said force-applying means being resilient while the other is adjustable.

JOHN H. TEAF. 

